The invention concerns processes and a device for unloading a mail piece container of the type having side walls slanting toward the outside, loaded with mail pieces that stand on edge next to one another, and exhibiting gripping recesses in its opposite smaller sides.
In mail piece distribution processes, slim mail pieces, letters for example, are transported in corresponding containers. To sort the mail pieces according to the recipients"" addresses in sorting apparatuses, the containers must be unloaded and the pieces fed to a material input. The unloading and feeding were accomplished manually in the past. Although a solution for the automatic feeding of sorting machine material inputs was described in DE 195 45 716 C1, the full container is, however, dumped forcefully on the material input. A gentle transition of the aligned mail piece stack, without danger of damage to the individual mail pieces, is not possible with this prior art. If it is also necessary to maintain the arrangement of the edges, then the stack must be turned back again. The edge arrangement necessary for further processing is not guaranteed using these processes.
It is thus the task of the invention, through utilization of a process, to make possible semi-automated or fully automated emptying of mail piece containers, of the type that are open at the top and have side walls that slant toward the outside, so that the mail pieces are unloaded gently, maintaining their orientation and arrangement.
This task is solved according to the invention through the steps of: (1) the mail piece container is taken up by a holding and positioning device that can be tilted, (2) compression of the mail piece stack within the horizontally aligned mail piece container having pressing elements that are movable horizontally through the gripping recesses, (3) engagement of the tilting and movable holding supports next to the pressing elements from above, in order to hold the mail piece stack in compressed form, with the conveyor bands of the holding supports being driven in such a way that the segments of the conveyor band in contact with the mail pieces are motionless with respect to the mail pieces, (4) removal of the pressing elements from the mail piece container, (5) tilting of the full mail piece container with the holding supports by  greater than 90xc2x0 around a longitudinal axis to the point that the mail piece stack can rest on the now lower side of the mail piece container, (6) tilting back of the mail piece container to the point that a movable and tiltable base plate can be inserted between the mail piece container and the mail piece stack, (7) insertion of the base plate between the mail piece container and the mail piece stack, (8) tilting back of the mail piece container, the base plate, and the mail piece stackxe2x80x94which is clamped between the holding supportsxe2x80x94to a horizontal position of the mail piece stack, while maintaining the positions of these elements with respect to one another and (9) detaching of the mail piece container from the holding and positioning device and removal of the mail piece container.
A corresponding device for unloading a mail piece container open at the top with side walls that slant toward the outside, which container is loaded with mail pieces that stand upright next to one another, and which container exhibits gripping recesses on its opposite narrow sides, is characterized by (1) horizontally movable pressing elements for compressing the mail piece stack, in a horizontal base position of the mail piece container, through the gripping recesses; (2) movable holding supports that can be tilted, having conveyor belts that can be driven, that take over the compressed mail piece stack in the container and hold it; (3) a holding and positioning device, which can be tilted, for the mail piece container; (4) a base plate that can be, tilted and moved; and (5) a control unit, as well as sensors, for realizing the process steps set forth above.
The mail pieces are unloaded through the indicated steps and means such that the aligned condition of the mail pieces is maintained and such that no forces occur that unsettle or crumple the mail pieces. In order to achieve this, during unloading, the stack is transported, compressed and clamped between holding supports with revolving conveyor bands. When the holding supports are engaged, the conveyor bands are moved so that no additional forces, besides the normal forces, act on the contacted mail pieces.
The tilting and translational movements are effected by means of a conventional and familiar handling system with numerically controlled axes, and is thus not represented in more detail here.